A catheter is a medical instrument generally comprising a rigid or flexible tubular device which can be placed within a human or animal body for the purpose of administering or excising gases, liquids or medicament. The device is placed into a body via existing orifices and channels or via apertures made through the skin into veins, arteries or other like internal body spaces and channels to arrive at a site where treatment is required. The application of skill and the exercise of great responsibility by a medical practitioner is solely responsible for its proper use.
A variety of catheters are known which are usually differentiated by their design for specific purposes. For example an acorn-tipped catheter is used in ureteropyelography to occlude the ureteral orifice and prevent backflow from the ureter during and following the injection of an opaque medium; angiographic catheter is a device through which a contrast medium (i.e. X-ray opaque) is injected for visualisation of the vascular system of an organ, such catheters may have preformed ends to facilitate selective locating (as in renal or coronary vessel) from a remote entry site and thus may be further named according to the site of entry and destination, as femoral-renal, brachial-coronary, etc.; a toposcopic catheter is a very small catheter that can pass through narrow, tortuous vessels to convey chemotherapy directly to brain tumours, a Swan-Ganz catheter is a soft, flow directed catheter with a balloon at the tip for measuring pulmonary arterial pressures and is introduced into the venous system (via basilic, internal jugular, or subclavian vein) and is guided by blood flow into the superior vena cava, the right atrium and ventricle and into the pulmonary artery. Many more catheter types than described above are at the disposal of medical practitioners to use.
The ultimate worth of a catheter is determined by the accuracy of the location of the tip of the device in the body and thereafter the delivery or drainage processes acts on the organ or the part most receptive to the applied treatment. It is common practice after the catheter is placed in the body by the medical practitioner, to X-ray the patient to ensure the correct location of the catheter tip. This involves time delays and adds cost and inconvenience to the treatment process. Alternatively, this procedure of X-ray checking is not always undertaken and the skill of the practitioner must be relied upon to achieve correct location. This circumstance arises when speedy treatment is necessary and the X-ray procedure introduces unacceptable delays.
It will be apparent that a means to provide the aforementioned benefits is also capable of being used to locate other instruments that may be used in the medical or other fields.